As a Supported method, Create a plugin in the Execute Method to modify the fetchXML of the account view as per your requirement (modify the fetchxml to accounts that only have parent account)
Execute: The execute event always gets fired when you open the views. Like from Main application view, lookup view, Advanced search view etc. (but not from associated views).
While registering this event, no primary entity name is required.
Input parameter: fetchxml - The fetchXML query sent.
Output parameter: fetchxmlresult - The resultant records of the fetchXML query